This invention relates generally to the field of machines, equipment or apparatuses used to test condoms for holes, excessively thin walls or other imperfections prior to packaging and distribution. More particularly, the invention relates to such machines, equipment or apparatuses that utilize electrical current to determine the presence of such imperfections.
Minute holes, tears, or excessively thin wall areas subject to failure during use are unacceptable and render a condom defective. By virtue of their intended use, it is absolutely essential that condoms provide a complete and impermeable barrier. Minute holes undetectable under visual inspection and excessively thin spots in the condom wall likely to fail in use must be discovered. Because the manufacturing process produces huge numbers of condoms at a high rate and because the material of construction, typically a latex or similar plastic, is purposely very thin and elastic, there is always likely to be a relatively small number of defective products in any production run. Because of this, every condom must be tested prior to packaging and distribution for sale to insure that no defective condoms are supplied to consumers.
One method to detect defective condoms is to utilize air or a vacuum, wherein the passage of any air or gas through the condom wall is detected and indicates a defect. A second method utilizes water to test for defects. Typically this involves placing the condom on an electrically conductive mandrel, immersing the condom in water containing an electrical lead and then attempting to pass a current through the water to the mandrel. The condom material acts as an insulating barrier between the water and the mandrel to prevent completion of the electrical circuit, but any hole in the condom will allow the circuit to be completed, indicating that the condom is defective. Advantages of this technique are that low electrical voltages are required and the use of water as a conductive medium provides full contact to all portions of the condom. The major drawback to this technique is that the condoms must be dried prior to packaging. Another drawback is that the technique does not provide an indication of excessively thin spots in the condom wall which may tear in use, since the thin material is still sufficient to prevent passage of current from the water to the mandrel.
A third method, and the method utilized in this invention, also takes advantage of the fact that the condom is an electrical insulator. The condom is placed onto a metal, i.e., electrically conductive, mandrel and the outer surface of the condom is then brought into contact with another electrically conductive member, such as a metal mesh, a pad or bristles. In some instances, the condoms are wetted prior to testing, although this is not preferred for the reasons set forth above. The condom prevents completion of a closed circuit to ground, unless there is a defect, in which case the current will arc through the hole, tear or thin-walled area and complete the circuit. This completed circuit indicates a defective condom, which is then discarded. When a conductive mesh material is utilized, the mesh is constructed so as to be very non-rigid so that it closely drapes against the condom on the conductive mandrel. The mandrel and condom are rotated while contacting the electrified mesh, and any defects will allow the current to pass through the condom to the mandrel. A problem with this technique is that because the mesh must have a large amount of open area to achieve the desired flexibility, direct contact against every portion of the condom is not achieved, so a relatively high and thus dangerous amount of electrical current must be used—typically greater than 50 watts—to try to insure that the current will arc from the mandrel through a defect to the nearest piece of mesh. The variation in distance from the condom to particular points on the mesh as the condom is moved past the mesh also makes proper calibration of the electrical current difficult. Another problem is presented by the nipple portion of the condom. Because of this change in configuration from the generally cylindrical main body portion of the condom, providing sufficient contact between the mesh and the nipple material is problematic and defects can be missed. Examples of testing equipment that utilizes this methodology are shown in U.S. Pat. No. 2,221,323 to Gammeter, U.S. Pat. No. 2,609,094 to Fry, and U.S. Pat. No. 2,649,960 to Gammeter.
An improved method and apparatus that utilizes completion of an electrical current to indicate defects in a condom, but which does not utilize a mesh material as one of the electrodes, is shown in U.S. Pat. No. 6,160,406 to Underwood et al., the disclosure of which is incorporated herein by reference. The exterior condom-contacting members comprise in combination an electrically conductive fabric member and an electrically conductive brush member, and may also comprise only fabric members or only brush members. For the combination fabric and brush assembly, the fabric member is positioned to contact the generally cylindrical main body portion of the condom as it is brought across the fabric member. The fabric member is sufficiently long in the mandrel direction of travel such that the condom is tested over its full circumference of 360 degrees, and preferably is provided excessively long such that more than one revolution of the condom is achieved during the test pass. The fabric member is not positioned to contact the far end of the nipple portion, as the friction from the rotational movement would twist and damage the condom. The brush member is positioned along the nipple portion, preferably at an angle to the central axis of the rotating mandrel, in order to contact the extreme end of the nipple portion. In this manner every point of the condom is in direct contact with either the conductive fabric member or the conductive brush member, such that the electrical current will complete the circuit through any minute hole in the condom to indicate a defective condom. Furthermore, because the contact between the condom and both the fabric member and brush member is so extensive, and because the fabric member and brush member are positioned relatively close to the mandrel and at a relatively constant distance, the current strength can be adjusted such that the circuit will be completed even through excessively thin-walled areas of the condom, thus indicating a defective condom even where a hole is not present initially. Alternatively, the fabric member may be omitted and the condom-contacting means formed entirely of one or more conductive brush members appropriately arranged to contact the full extent of the exposed condom on the mandrel. In this construction means such as a geared or friction mechanism are required to rotate the mandrel as it is passed across the brush member, since the coefficient of friction between the brush members and the mandrel would be insufficient to rotate the mandrel unaided.
It is common in testing equipment of the various types described above to mount a plurality of mandrels onto a rotating table, track or platform in a circular pattern. With this construction, it is possible to provide a loading station, a testing station and a removal station, each spaced along the travel pathway of the mandrels, such that the table can be rotated continuously in a single direction. The condoms are individually loaded onto empty mandrels, which then travel through the testing zone to identify any defective condoms. The condoms are then removed from the mandrels, with the defective condoms being separated and discarded. Loading of the condoms onto the mandrels may be accomplished manually or by automated equipment. Likewise, removal of the condoms may be accomplished manually or by automatic equipment, although the use of automatic removal and separating equipment in communication with the testing equipment is typical. Loading, removal and separating equipment of various types are well known in the art.
In this type of condom defect testing equipment, the minimum distance between adjacent mandrels on the platform, table or track is determined by the circumference of the test mandrels themselves. A typical mandrel may be approximately 5.81 inches in circumference, as it is necessary to provide a uniform stretch on the condom during testing. Since the known condom testing equipment utilizes a single electrically conductive mesh, pad or brush to test each individual condom, with the condom and mandrel being rotated in excess of 360 degrees as it travels across the electrically conductive mesh, pad or brush, the length of the mesh, pad or brush in the mandrel travel direction must be of a distance in excess of the circumference of the loaded mandrel. In practice, this length dimension must also include an additional distance beyond the mandrel circumference as a safety factor to insure that the complete circumference of each condom is tested, so that typically at least 125 percent of the circumference is tested. Since more than one condom cannot be in contact with the mesh, pad or brush during a given test procedure, the mandrels must also be separated a distance greater than the length of the testing mesh, pad or brush. This separation requirement limits the number of mandrels that can be positioned on the rotating table, which in turns limits the testing rate for the condoms. In a typical automatic loading test apparatus, for example, the mandrels are typically separated a distance of approximately 10 inches and the maximum travel rate or rate of rotation is about 12 inches per second.
Because the maximum travel rate is limited, especially with regard to manual loading, an apparatus that enables the mandrels to be more closely spaced will increase the number of condoms that can be tested over a given time period. Condom testing equipment with automatic condom loading typically test about 100 condoms per minute, while manually loaded testing equipment typically test about 50 to 60 condoms per minute. While increasing the testing rate of either type is desirable, the manual loading test equipment is much cheaper and occupies significantly less floor space than automatic loading test equipment, and thus it is especially desirable to increase the testing rate on the manual loading apparatuses.
It is an object of this invention to provide an improved condom testing apparatus and methodology which address the problems described above in terms of increasing the testing rate of condoms, especially with regard to manual loading condom testing apparatuses, in that the distance between condom-containing mandrels is minimized. It is an object to provide such an apparatus wherein the defects in a condom are detected upon passage of an electrical current between an electrically conductive mandrel and multiple external condom-contacting electrode members through any defect in the condom such that a closed circuit is formed. It is an object to provide such an apparatus wherein the length of any of the condom-contacting electrode members in the direction of travel of the mandrel is less than the circumference of the mandrel, such that at least two sets of condom-contacting electrode members are required to test the entire circumference of the condom, in that neither set of condom-contacting electrode members individually tests the full circumference of the condom. It is an object to provide such an apparatus wherein a second condom-containing mandrel is tested on the first set of condom-contacting electrode members simultaneously with a first condom-containing mandrel being tested on the second set of condom-contacting electrode members, the first condom-contacting mandrel having been already tested on the first set of condom-contacting electrode members and advanced to the second set of condom-contacting electrode members. These objects, as well as objects not expressly set forth, will be apparent upon examination of the disclosure that follows.